Question

The volume of a cone is 251.2 cubic inches. The height of the cone is 15 inches. What is the radius of the cone, rounded to the nearest inch? Use π = 3.14.

16 inches
8 inches
6 inches
4 inches

Answer 1

@dan815

Answer 2

What we have to do with this question is work backwards. Do you know the formula to find the volume of a cone?

Answer 3

yes. i know that i have to work backwards, i just got an answer not an answer choice

Answer 4

What did you do to get your answer?

Answer 5

idek!

Answer 6

Okay let me show you how I would do it. Volume of cone = \[\frac{ 1 }{ 3 }\pi r^2 h\] (where r is radius and h is height).

Answer 7

So we could just substitute the values we already have to find the values that are unknown; \[251.2=\frac{ 1 }{ 3 } 3.14 * r^2*15\]

Answer 8

I'm sorry if that's a bit hard to read but do you understand so far?

Answer 9

yes

Answer 10

@Sepeario

Answer 11

Then we have \[251=3.14/3 * 15 * r^2\]
\[251=(3.14*15)/3 * r^2\]
\[251=15.7r^2\]

Answer 12

\[251/15.7=r^2\]
The radius squared approximately equals 16, and the radius hence is 4.

Answer 13

so the radius is 4?

Answer 14

Yes.

Answer 15

so d?